On Friday the 29-year-old running back announced in a tweet entitled "Why I'm not in the NFL" that he is retiring due to a spinal cord injury.

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"To those who are wondering why I am not playing anymore," Redman posted to his Twitter account. "Last season I tried my best to play through a neck injury but I just wasn't myself on the field.

"After being released I went (to) Cali to see Dr. Watkins (doctor who did Payton [sic] Manning's neck surgery) after 2 MRI's and a (CAT) scan he then told me I had suffered a career ending injury to my spinal cord. Various teams have called but as you can see I was unable to go. I would like to thank all my fans for the tremendous support throughout my career."

In five seasons -- all with the Steelers -- Redman earned 1,148 yards on 282 attempts and five touchdown rushes. Redman was diagnosed with a concussion in Week 2 last season and Pittsburgh cut the runner after just three games.

Redman went undrafted in 2009 out of Bowie State, a Division II university.